What is an oscillating molecular dipole defined as?

[apeters]

Is an oscillating dipole of a molecule the periodic motion of the atoms in the molecule (the oscillating back and forth of a more negatively charged atom and more positively charged atom), or, is an oscillating molecular dipole just oscillations in electron density? I just can't get a clear answer on this.

 

[DrDu]

Both. While the motion of the nuclei is in the frequency range of infrared light, the oscillation of the electronic charge density occurs at frequencies in the visible and ultraviolet part of the spectrum. Hence they lead to absorption lines or bands in the respective IR and UV-Vis spectra.

 

[DrDu]

Both. While the motion of the nuclei is in the frequency range of infrared light, the oscillation of the electronic charge density occurs at frequencies in the visible and ultraviolet part of the spectrum. Hence they lead to absorption lines or bands in the respective IR and UV-Vis spectra.